I 've installed both getlocale.tcz and base_locale.tcz from x86 repos with deps from armv7 as you said.
In 7.1b4 system (I haven't a second microSD flash, so before i decided to try on current system).
Of cource I used deps from 7.x armv7 app version branch.
When getlocale.sh asked me for locales, i checked en_US.UTF-8/UTF-8 and ru_RU.UTF-8/UTF-8 only.
The mylocale.tcz is generated, and as result i got mylocale.tcz and base_locale.tcz packages installed.
But now I get a question, how i can set up boot args to set lang to new locale???
F2, F3, F4 keys don't work at boot time on Raspberry Pi - it uses different bootstrap scheme rather then classis x86 PCs.